In the conventional mobile communication system for mainly serving personal mobile communication devices, there is an inverse proportional relationship between the speed of the UE and required data rate and quality of service (QoS). So, the conventional communication system is configured to provide high data rate/QoS for low speed UE, and to provide reliable service without radio link failure for the high speed UE even if the data rate/QoS is somewhat low.
In the next generation communication system, there is a need for high data rate/QoS for the high speed UE, since the scope of the required service increase. For example, the users in the vehicle or public transportation would like to enjoy multi-media service during the drive on a highway. Also, users want to enjoy multi-media service more while the speed of the vehicle is high.
This is a new model which does not exist in conventional wireless communication service models. To support this, mobile communication networks need to be enhanced to a revolutionary level or a new system capable of realizing the new model without affecting network infrastructures needs to be designed.
In next-generation mobile communication systems, V2X (Vehicle-to-Infrastructure/Vehicle/Nomadic) communication technology for supporting efficient vehicle communion is under discussion. V2X communication includes communication between a vehicle and infrastructure (V2I) and communication between vehicles (V2V).
When a large antenna array is provided to the outside of a vehicle in order to provide a high quality communication service to high speed vehicles, aesthetic/aerodynamic problems are generated and thus research into vehicle antennas for replacing the large antenna array is required.
In addition, when an event that a signal of a serving cell decreases below a specific threshold value compared to neighboring cells in order to manage UE mobility occurs, a UE reports occurrence of the event to the serving cell for UE mobility management in a conventional technology. However, efficiency of application of this technology to vehicular communication needs to be examined.